Adversaries may perform Denial-of-Service (DoS) attacks to disrupt expected device functionality. Examples of DoS attacks include overwhelming the target device with a high volume of requests in a short time period and sending the target device a request it does not know how to handle. Disrupting device state may temporarily render it unresponsive, possibly lasting until a reboot can occur. When placed in this state, devices may be unable to send and receive requests, and may not perform expected response functions in reaction to other events in the environment.
Some ICS devices are particularly sensitive to DoS events, and may become unresponsive in reaction to even a simple ping sweep. Adversaries may also attempt to execute a Permanent Denial-of-Service (PDoS) against certain devices, such as in the case of the BrickerBot malware. 
Adversaries may exploit a software vulnerability to cause a denial of service by taking advantage of a programming error in a program, service, or within the operating system software or kernel itself to execute adversary-controlled code. Vulnerabilities may exist in software that can be used to cause a denial of service condition.
Adversaries may have prior knowledge about industrial protocols or control devices used in the environment through Remote System Information Discovery. There are examples of adversaries remotely causing a Device Restart/Shutdown by exploiting a vulnerability that induces uncontrolled resource consumption.   
In the Maroochy Shire attack, the adversary shut an investigator out of the network.
The Industroyer SIPROTEC DoS module exploits the CVE-2015-5374 vulnerability in order to render a Siemens SIPROTEC device unresponsive. Once this vulnerability is successfully exploited, the target device stops responding to any commands until it is rebooted manually.  Once the tool is executed it sends specifically crafted packets to port 50,000 of the target IP addresses using UDP. The UDP packet contains the following 18 byte payload: 0x11 49 00 00 00 00 00 00 00 00 00 00 00 00 00 00 28 9E. 
System and process restarts should be performed when a timeout condition occurs.
|ID||Data Source||Data Component||Detects|
|DS0015||Application Log||Application Log Content||
Monitor for application logging, messaging, and/or other artifacts that may result from Denial of Service (DoS) attacks which degrade or block the availability of services to users. In addition to network level detections, endpoint logging and instrumentation can be useful for detection.
|DS0029||Network Traffic||Network Traffic Content||
Monitor and analyze traffic patterns and packet inspection associated to protocol(s) that do not follow the expected protocol standards and traffic flows (e.g., extraneous packets that do not belong to established flows, gratuitous or anomalous traffic patterns, anomalous syntax, or structure). Consider correlation with process monitoring and command line to detect anomalous processes execution and command line arguments associated to traffic patterns (e.g., monitor anomalies in use of files that do not normally initiate connections for respective protocol(s)).
|Network Traffic Flow||
Monitor network data for uncommon data flows. Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious.
|DS0040||Operational Databases||Process History/Live Data||
Monitor operational data for indicators of temporary data loss which may indicate a Denial of Service. This will not directly detect the technique’s execution, but instead may provide additional evidence that the technique has been used and may complement other detections.